2 Answers
2

self is an implicit parameter in objective-c of instance methods that refers to the object performing the method - see here: Messages to Self and Super

In this case, self.faceView is a call to the property accessor for faceView that is bound to the instance that runs this method, while the assignment _faceView= faceView; is assigning the input parameter faceView to the iVar _faceView. self.faceView.dataSource = self; assigns the object performing this method to the dataSource property of the object's faceView property.